How to Solve (255^2) - (245^2) Mentally

How to mentally solve the expression (255^2) - (245^2), employing the approach likely used by Scott Wu during the 2010 Raytheon MATHCOUNTS National Competition.

[@Poxle.]

Very good video, I was trying to think of the strategy that was used on this equation, very helpful thank you.

[@snehalmittal1261]

nicee